There are a number of medicament delivery devices on the market that are intended for self-administration. These devices have different degrees of functionality and thus complexity both regarding number of interacting components and handling of the actual device for delivering a dose of medicament.
In order that the patient or user is alerted regarding the state of the device for example regarding the number of doses that have been delivered or are remaining as well as the dose size, if the user may set different dose sizes, some devices are arranged with indicia visible through openings or windows in the device for mechanical dose information mechanisms or electronic displays if the device is provided with electronic dose information mechanisms.
Regarding mechanical dose information mechanisms, indicia are often arranged on an outer surface of a rotatingly arranged member, which during dose setting and/or dose delivery rotates a certain amount, which is displayed in the opening or window of the device. This function is adequate for many devices where the doses are rather large and/or that the rotation of the dose information member is to such an extent that all the indicia to be shown can fit onto the surface of the member.
However, for some devices and in particular when the dose increments are rather small, or the movement of the indicia member is rather small for a set dose, all indicia to be shown cannot fit onto the surface of the member which leads to problem regarding providing the user with the appropriate information.
There is thus a need for improvement regarding electromechanical dose information mechanisms that can handle small dose increments such that the proper information is provided to the user, e.g. having some sort of transmission or the like in order to handle movement of components of a medicament delivery device.
WO2008037801 discloses an injection device having a dose setting mechanism comprising linear capacitive sensors. The measurement is performed by analogue capacitance measurements which are then converted to digital form. The means for electronically detecting the amount of a set dose and/or the means for electronically detecting the amount of an injected dose may comprise at least two substantially disc shaped members being arranged with a substantially fixed mutual distance along a longitudinal direction of the injection device, said substantially disc shaped members being rotationally movable relatively to each other during dose setting and/or injection, and an angular displacement between said substantially disc shaped members may in this case be indicative of the amount of a set dose and/or the amount of an injected dose.
WO2007116090 discloses an injector having a complex dose setting mechanism comprising several electrodes on the outer surface of a dose indication barrel connected to contact members of an electronic device, and wherein said contact members are arranged to be slide across said electrodes when said barrel is rotated.
WO2007141225 discloses a medication delivery device having a dose setting mechanism which comprises first and second transmitter electrodes and a receiver electrode positioned on the inner surface of a housing and an axially movably member having a reflector electrode, wherein the reflector electrode is adapted to be capacitive coupled to at least one of the transmitter electrodes and to the receiver electrode, such that when said transmitter electrodes are provided with transmitter signals the axial position of the movably member is detected by the receiver electrode. The measurement is performed by analogue capacitance measurements which are then converted to digital form.
US2004135078 discloses a medication delivery device having a dose setting mechanism with an optical sensor.